Toroids are plenty.
Ringkern-Transformator SE-RKT offen - hifituning24.de
Some say that they couple more dirt into the circuit though.
Ringkern-Transformator SE-RKT offen - hifituning24.de
Some say that they couple more dirt into the circuit though.
Can it be possible to avoid the zeners as Vref ? Maybe using a resistor over a ccs ?
That way the whole thing could be tuned by carefully choosing the resistor bypass cap
And I sometimes have noise issues with zeners (even 27v ones) and I guess 24v ones are the same. Super low noise zeners exist but.....
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Can it be possible to avoid the zeners as Vref ? Maybe using a resistor over a ccs ?
That way the whole thing could be tuned by carefully choosing the resistor bypass cap
And I sometimes have noise issues with zeners (even 27v ones) and I guess 24v ones are the same. Super low noise zeners exist but.....
Yes you can, like in the Salas shunt regulator.
My circuits always use toroid’s, and I always use a mu-metal box to separate the transformer from the rest of the box. I do like the dynamic behavior of the toroid although this is not the most important for small signal circuits.
Balanced RIAA preamp | Flickr - Photo Sharing!
The inter-winding capacitance is higher certainly. However, good filtering on the mains side and a solid inter winding screen go a long way to making the differences quite minimal.
R-cores are a great buzz word for the high end audio industry.
Can it be possible to avoid the zeners as Vref ? Maybe using a resistor over a ccs ?
That way the whole thing could be tuned by carefully choosing the resistor bypass cap
And I sometimes have noise issues with zeners (even 27v ones) and I guess 24v ones are the same. Super low noise zeners exist but.....
A string of LED's is also possible. Use a selected resistor (trimmer) for R7. The more LED's the better; I would say a minimum of five.
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If the circuit consumes 100mA then I need to recalculate the power supply for a current source of 150mA. Can you tell me what the maximum consumption of one mono channel will be (I guess we go for full dual mono).
Non linearly though, because uncorrelated. You got to sum their squares and then sqrt that number.
Given that the zener's may be a bit inconsistent, you may still like to select LED's for the reference. Using a string of 12 Yellow LED's would (Vrms added) generate about 1.3uV down to 1uV (being very optimistic) of noise (according to the list). I would say, we make place for the string of LED's and the builder can always stuff an zener diode in their place.
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Frans, you are very pragmatic and i like that. Yes, we should make place for some Leds.
I personally have no problem with toroids either. I agree that the transformer should be in another compartment or in a separate box. This is the only way to avoid hum in a low lever circuit like that. Your preamp looks great inside. I like the copper pipes.
MiiB, that is what i was expecting. Gain goes up and so does distortion. -96dB is of cause excellent and the distortion distribution looks great. The only think i would like to see is when you go back from 50 Ohm degeneration to 20 Ohm and adjust the RIAA again for a gain of 61dB. If we get out the same distortion then the 20 Ohm degeneration would give somewhat less noise. I think after that experiment, we fix the parameters.
I personally have no problem with toroids either. I agree that the transformer should be in another compartment or in a separate box. This is the only way to avoid hum in a low lever circuit like that. Your preamp looks great inside. I like the copper pipes.
MiiB, that is what i was expecting. Gain goes up and so does distortion. -96dB is of cause excellent and the distortion distribution looks great. The only think i would like to see is when you go back from 50 Ohm degeneration to 20 Ohm and adjust the RIAA again for a gain of 61dB. If we get out the same distortion then the 20 Ohm degeneration would give somewhat less noise. I think after that experiment, we fix the parameters.
Thanks
and yes I think so Here a version with the filter, snubber resistors and LED's. The current has now been set to 150mA ( 105mA for the amplifier, 45mA to warm the planet).
